Prior patents disclose foldable sofa bed assemblies having linkage mechanisms provided for shifting folded bed frames into and out of a base structure and for stablizing the bed frames securely in its two positions of use. For example, the U.S. Pat. No. of Inman 3,771,178 discloses a linkage mechanism which is connected to a base means and is adapted for connection to two frame means to be operable for movement between the sofa and bed forming positions without being connected to the two frame means. Likewise, the U.S. Pat. No. of Hill 3,482,270 discloses a daveno bed provided with a raising and lowering mechanism having a cross shaft and a tie rod extending across the width of the bed frame and which interconnects the main supporting pivotal arms.
This invention relates to a foldable sofa bed assembly of the type which is normally in the sofa forming position whereby it may be utilized for seating but may be unfolded for a bed forming position so that it may be utilized as a bed. Such assembly typically includes at least two frame subassemblies which are pivotly connected together and which are generally coplanar for supporting a mattress when in the bed forming position.
The prior art sofa bed assemblies typically include some sort of base frame which is adapted for attachment to a wooden frame of a piece of furniture. Various linkage mechanisms are utilized for interconnecting the two bed forming frames with the base frame to accommodate movement of the two bed forming frames between the bed forming position and the sofa forming position. These linkage mechanisms include a significant number of links which are normally pivotally connected to one another and to the two bed forming frames. Typically the manufacturers of such assemblies must attach linkages to the base frame and to the two bed forming frames for shipping the entire assembly to the customer when installed into the furniture frame which is also shipped to customer. Thereafter the manufacturer applies the upholstery. Most assemblies have therefore been shipped with the linkages attached to the bed forming frames. The assemblies are shipped in the sofa forming position where the bed forming frames overlie and are spaced vertically from one another. The space between the vertically separated bed forming frames during shipment is wasted and costly shipping space results.
The manufacturers of such assemblies also typically ship the back frame subassembly fully assembled ready for the attachment of upholstery including a back cushion. However, the configuration of the back frame assembly when so assembled also causes a waste of shipping space which is costly.